1. Field of the Invention
The present invention relates to quick connectors/disconnectors for electrical circuits, and more particularly, to an explosion-proof instrument quick disconnect and seal for use in hazardous environments to quickly connect or disconnect electrical circuits.
2. Description of the Related Art
There are many applications today where electrical connections are made in hazardous (e.g., explosive) environments, such as locations where ignitable concentrations of flammable gases, vapors or liquids are present or may become present through accident or abnormal operation. For instance, Article 500 of the National Electrical Code (xe2x80x9cNECxe2x80x9d) has classified certain locations as hazardous, including Class I (combustible material in the form of gas vapors) and Class II (combustible material in the form of dust).
In most modem industrial applications, electrical wiring/cable passes through a conduit system from location to location, such as from an enclosure housing of an electronic instrument to terminals in junction boxes outside the instrument or to the plant electrical and instrumentation distribution systems. Electrical circuits present certain inherent risks in hazardous environments because electrical sparks or arcing may occur when an electrical circuit is made or disconnect using a plug and receptacle due to the sudden flow or interruption of electrical energy. For this reason, NEC requires that conduit connections in certain hazardous environments be sealed with an approved explosion-proof seal fitting to prevent hazardous gases from traveling through the conduit system in the event of an internal explosion and to prevent a flame or an internal explosion from igniting the surrounding atmosphere.
In such hazardous environments, it is known to install explosion-proof seal fittings at various locations along the conduit system to prevent the passage of gases, vapors or flames from one portion of the electrical installation to another through the conduit. These conventional seal fittings typically have an opening through which a sealing compound or cement is introduced to literally seal the conduit and wire/cable contained therein at that location. However, these seal fittings are expensive and their installation is labor intensive. Furthermore, removal of the seal (e.g., for maintenance or service of the electrical system) is exceedingly difficult and typically requires either cutting the seal fitting off of the conduit system (which may also result in cutting the wire/cable contained therein) or chipping away the sealing compound contained within the fitting.
Accordingly, it is desirable to have a device for quickly connecting or disconnecting live electrical circuits in indoor and outdoor hazardous areas that includes an explosion-proof seal for preventing hazardous gases, vapors or liquids from traveling through the conduit system in the event of an internal explosion and to prevent a flame or internal explosion from igniting the surrounding atmosphere.
These and other objects of the present invention are accomplished through the use of an explosion-proof instrument quick disconnect to be used in hazardous (e.g., explosive) environments to quickly connect or disconnect energized or de-energized electrical circuits. The device also acts as an explosion-proof conduit seal in which a sealing compound is poured through the ends where wire/cable exits the connector, therefore meeting the requirements of the NEC and eliminating the need for separate seal fittings surrounding the device.
The explosion-proof instrument quick disconnect and seal comprises a first portion having a first bore extending therethrough from a proximal end to a distal end. A second portion is detachably coupled to the first portion and has a second bore extending therethrough from a first end to a second end. The second end of the second portion is received within the first bore of the first portion to define an explosion-proof chamber within the first and second portions when the first and second portions are coupled to one another. First and second electrical inserts, each having electrical contacts, are positioned within the first bore of the first portion and second bore of the second portion, respectively. Each of the electrical contacts in the first electrical insert engage and form an electrical connection with a respective electrical contact in the second electrical insert within the explosion-proof chamber when the first and second portions are coupled to one another.
The foregoing specific objects and advantages of the invention are illustrative of those that can be achieved by the present invention and are not intended to be exhaustive or limiting of the possible advantages which can be realized. Thus, these and other objects and advantages of this invention will be apparent from the description herein or can be learned from practicing this invention, both as embodied herein or as modified in view of any variations which may be apparent to those skilled in the art. Accordingly, the present invention resides in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.